Remove DelayedCall debugging from test runs (#5787)

changelog.d/5787.misc

@@ -0,0 +1 @@
+Remove DelayedCall debugging from the test suite, as it is no longer required in the vast majority of Synapse's tests.

tests/unittest.py

@@ -23,8 +23,6 @@ from mock import Mock
 
 from canonicaljson import json
 
-import twisted
-import twisted.logger
 from twisted.internet.defer import Deferred, succeed
 from twisted.python.threadpool import ThreadPool
 from twisted.trial import unittest
@@ -80,10 +78,6 @@ class TestCase(unittest.TestCase):
 
         @around(self)
         def setUp(orig):
-            # enable debugging of delayed calls - this means that we get a
-            # traceback when a unit test exits leaving things on the reactor.
-            twisted.internet.base.DelayedCall.debug = True
-
             # if we're not starting in the sentinel logcontext, then to be honest
             # all future bets are off.
             if LoggingContext.current_context() is not LoggingContext.sentinel: